The effects of humidity on phthalocyanine NO₂and NH₃sensors

Abstract

The effect of humidity on the behaviour of metal phthalocyanine (MPc) gas sensors has been studied for an electron donor gas (NH3) and an acceptor (NO2). Water vapour acts as an effective donor even in the presence of a strong donor adsorbate such as NH3. In this case the water vapour enhances device sensitivity and reduces response and recovery times. NiPc is found to display much greater humidity sensitivity than the other metal Pc's studied. For the PbPc-NO2 system at room temperature, the water overcompensates the NO2 acceptor adsorbate. The results with PbPc support previous observations that a PbPc NO2 sensor is only viable at elevated operating temperatures.